Dynamic Molecular Investigation of the Solid-Electrolyte Interphase of an Anode-Free Lithium Metal Battery Using In Situ Liquid SIMS and Cryo-TEM

Journal Article · Wed Sep 13 00:00:00 UTC 2023 · Nano Letters

DOI: https://doi.org/10.1021/acs.nanolett.3c00709 · OSTI ID:2305717

Cheng, Cuixia  ^[1]; Zhou, Yadong ^[2]; Xu, Yaobin  ^[2]; Jia, Hao  ^[2]; Kim, Jumyeong ^[2]; Xu, Wu  ^[2]; Wang, Chongmin  ^[2]; Gao, Peiyuan  ^[2]; Zhu, Zihua  ^[2]

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1. Hubei Normal University, Huangshi (China); Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)
2. Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)

Solid electrolyte interphase (SEI) has been widely perceived to play a critical role in the stable cycling of rechargeable batteries. However, associated with the fragile and air-sensitive nature of the SEI layer, delineation of the formation process and the nature of SEI remains a big challenge. Here, we use in situ liquid time-of-flight secondary ion mass spectroscopy (TOF-SIMS), cryo- transmission electron microscope (TEM) and density functional theory (DFT) calculation to delineate molecular process on the formation of SEI layer under the dynamic operating condition. We discover that the onset potential for SEI layer formation and the thickness of the SEI show dependence on the solvation shell structure. Using LiCoO₂ as a cathode and Cu film as an anode, the SEI is noticed to start to form at around 2.0 V and reach its final thickness (irreversible part, ~ 40-50 nm) at about 3.0 V in the 1 M LiPF₆–EC/DMC electrolyte, while for the case of 1 M LiFSI–DME, the SEI starts to form at around 1.5 V and reaches its final thickness (~ 20 nm) at about 2.0 V. The in situ TOF-SIMS clearly indicates the outer SEI layer formation and dissipation upon charging and discharging, implying a continued evolution of electrolyte structure with extended cycling. In conclusion, the present work establishes a direct correlation between the molecular signature of SEI layer with solvation feature of electrolytes in lithium batteries, providing insights for tailoring SEI layer toward improved electrochemical properties of lithium batteries.

• Research Organization: Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)
• Sponsoring Organization: Hubei Provincial Natural Science Foundation of China; USDOE Laboratory Directed Research and Development (LDRD) Program; USDOE Office of Science (SC), Basic Energy Sciences (BES). Scientific User Facilities (SUF); USDOE Office of Science (SC), Biological and Environmental Research (BER)
• Grant/Contract Number: AC05-76RL01830
• OSTI ID: 2305717
• Report Number(s): PNNL-SA--185620
• Journal Information: Nano Letters, Journal Name: Nano Letters Journal Issue: 18 Vol. 23; ISSN 1530-6984
• Publisher: American Chemical SocietyCopyright Statement
• Country of Publication: United States
• Language: English